Running completely from NAND flash, I'm seeing a huge discrepancy between disk usage numbers from "df" and "du". The former says I'm using 502 KB, while the latter can account for no more than 327 KB. Twice, without realizing this mismatch and thinking simply that I installed too many things, I went in and cleaned out a bunch of stuff to free up memory. Both times the usage went back up to 99% while I was looking the other way. What's going on? How do I track the culprit down?

I seem to be constantly running out of space on the NAND flash. I don't want to go out and buy an SD card just yet.. Is it possible/advisable to place rootfs on teh ext3 formatted USB drive? How can I go about doing it?